It has long been desired to maximize fuel economy, power and driveability in diesel fuel powered vehicles while enhancing acceleration, reducing emissions, and preventing hesitation. While it is known to enhance gasoline powered engine performance by employing dispersants to keep valves and fuel injectors clean, such gasoline dispersants are not necessarily effective in diesel fuel applications. The reasons for this unpredictability lie in the many differences between how diesel engines and gasoline engines operate and the chemical differences between diesel fuel and gasoline.
Furthermore, low sulfur diesel fuels, ultra low sulfur diesel fuels and high pressure common rail (HPCR) engines are now common in the marketplace. A “low sulfur” diesel fuel means a fuel having a sulfur content of 50 ppm by weight or less based on a total weight of the fuel. An “ultra low sulfur” diesel fuel (ULSD) means a fuel having a sulfur content of 15 ppm by weight or less based on a total weight of the fuel. Fuel injectors in an HPCR engine perform at much higher pressures and temperatures compared to older style engines and fuel injection systems. The combination of low sulfur or ULSD and HPCR engines have resulted in a change to the type of injector deposits and frequency of formation of injector deposits now being found in the marketplace.
Over the years, dispersant compositions for diesel fuel have been developed. Dispersant compositions known in the art for use in diesel fuel include compositions that may include polyalkylene succinimides, which are the reaction products of polyalkylene succinic anhydrides and amines. Dispersants are suitable for keeping soot and sludge suspended in a fluid, however dispersants are not particularly effective for cleaning surfaces once deposits have formed on the surfaces. Hence, diesel fuel compositions containing low sulfur diesel fuels or ULSD used in new engine technologies often still produce undesirable deposits in diesel engine injectors. Accordingly, improved compositions that can prevent deposit build up, maintaining “as new” cleanliness for the vehicle life are desired. Ideally, the same composition that can clean up dirty fuel injectors restoring performance to the previous “as new” condition would be equally desirable and valuable in the attempt to reduce air borne exhaust emissions.
In accordance with the disclosure, exemplary embodiments provide a diesel fuel, a diesel fuel additive concentrate and a method for improving the performance of fuel injectors for a diesel engine are provided. The diesel fuel includes a major amount of middle distillate fuel having a sulfur content of 50 ppm by weight or less; and a reaction product of (a) a hydrocarbyl substituted dicarboxylic acid or anhydride, and (b) an amine compound or salt thereof of the formula
wherein R is selected from a hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms, wherein the reaction product contains less than one equivalent of an amino triazole group per molecule of reaction product, and wherein the reaction product is present in an amount sufficient to improve the performance of diesel direct and/or indirect fuel injectors.
Another embodiment of the disclosure provides a method of improving the injector performance of a fuel injected diesel engine. The method includes operating the diesel engine on a fuel composition that includes a major amount of diesel fuel having a sulfur content of 50 ppm by weight or less and a minor amount of a reaction product derived from (a) a hydrocarbyl carbonyl compound of the formula
wherein R2 is a hydrocarbyl group having a number average molecular weight ranging from about 200 to about 3000 and (b) an amine compound or salt thereof of the formula
wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product is characterized by an FTIR spectrum having a peak intensity in a region of from about 1630 cm1 to about 1645 cm−1 that ranges from about 5 to about 45% of peak intensities of other peaks in a region of from about 1500 cm−1 to about 1800 cm−1.
A further embodiment of the disclosure provides a method of cleaning fuel injectors of a fuel injected diesel engine. The method includes operating the diesel engine on a fuel composition including a major amount of diesel fuel having a sulfur content of 50 ppm by weight or less and a minor amount of a reaction product derived from (a) a hydrocarbyl carbonyl
wherein R2 is a hydrocarbyl group having a number average molecular weight ranging from about 200 to about 3000 and (b) an amine compound or salt thereof of the formula
wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product contains less than one equivalent of an amino triazole group per molecule of reaction product.
An advantage of the fuel additive described herein is that the additive may not only reduce the amount of deposits forming on direct and/or indirect diesel fuel injectors, but the additive may also be effective to clean up dirty fuel injectors.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.